Biology operons/bacteria/viruses

bacteria

single celled prokaryotes

circular

bacteria have singular _____ chromosome

Naked DNA

DNA not associated with histones or histone-like proteins.

Plasmid

A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome

horizontal gene transfer

The transfer of genes between organisms in a manner other than traditional reproduction.

vertical gene transfer

transmission of genes from the parental generation to offspring via sexual or asexual reproduction

sources of variation

mutation, transformation, transduction, conjugation, transposons

spontaneous mutation

a random change in the DNA arising from errors in replication that occur randomly

E. Coli

example of a spontaneous mutation

transformation

process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria; pick up foreign DNA wherever

R plasmids

carry genes for antibiotic resistance

swapping

resistant genes are on plasmids that are ____ between bacteria

transduction

phage viruses carry bacterial genes from one host to another

conjugation

bacteria sex

conjugation

the direct transfer of DNA between two cells that are temporarily joined

conjugation

"male" extends sex pilli and attatches to "female" bacterium

transposons

(jumping genes) short strands of DNA capable of moving from one location to another within a cell's genetic material

transposon

cut and paste

retrotransposon

copy and paste

Bacterial metabolism

Bacteria need to respond quickly to changes in their environment

feedback inhibition

product acts as an allosteric inhibitor

gene regulation

the turning on and off of genes

build

if bacterium has enough tryptophan then it doesnt need to make enzymes used to _____ tryptophan

digest

If bacterium encounters new sugar like lactose, then it needs to start making enzymes used to ____ lactose

operon

group of genes operating together

promoter

specific region of a gene where RNA polymerase can bind and begin transcription

operator

Region of DNA that controls RNA polymerase's access to a set of genes with related functions; binding site of repressor protein

repressor protein

a regulatory protein that binds to an operator and blocks transcription of the genes of an operon

repressible operon

transcription is usually on, but can be inhibited (repressed) when a specific small molecule binds allosterically to a regulatory protein (example tryptophan)

repressible

tryptophan is a ____ operon

synthesis pathway model

When excess tryptophan is present, it binds to tryp repressor protein & triggers repressor to bind to DNA, blocks (represses) transcription

Inductible operon

When substance is present - turn on operon

digestive pathway model

When lactose is present, binds to lac repressor protein & triggers repressor to release DNA, induces transcription

allosteric inhibition

lactose is an _____ regulator of repressor protein

Inductible

default setting is off

repressible

default setting is on

CAP

ust bind to cAMP to activate transcription of the lac operon by RNA polymerase

cAMP

When glucose levels decline in E. coli, catabolite activator protein (CAP) is bound by ____to promote transcription of the lac operon.

cAMP

when levels of this become high levels of glucose are low

CAP

when glucose levels increase in E. Coli, ____ detatched from the Lac operon, turning it off

Gene regulation

bacteria preform ___ _____ in order to conserve energy

epigenetics

the study of influences on gene expression that occur without a DNA change

DNA packing

coiling and folding of DNA in each chromosome

nucleosomes

"beads on a string", 1st level of DNA packing, histone proteins

packing

degree of ___ DNA regulates transcription (ex. "lightly packed around histones=no transcription, genes turned off)

Methylation

addition of a methyl group, blocks transcription factors,genes turned off

acetylation

addition of acetyl group, unwinds DNA, enables transcription

transcription initiation

RNA polymerase binds to promoter

promoter

specific region of a gene where RNA polymerase can bind and begin transcription, nearby control, base rate

enhancer

A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes, distant control, high rate

transcription complex

the completed assembly of transcription factors and RNA polymerase II bound to the promotor

post transcriptional control

Alternative RNA splicing, variable processing of exons creates a family of proteins

regulation of mRNA degredation

Life span of mRNA determines amount of protein synthesis, mRNA can last from hours to weeks

RNA interference

technique to silence the expression of selected genes in nonmammalian organisms; uses synthetic double-stranded RNA molecules matching the sequence of a particular gene to trigger the breakdown of the gene's messenger RNA

siRNA

short segments or RNA, bind to mRNA, create sections of double stranded mRNA, 'death tag' for mRNA, triggers degradation

gene silencing

A gene that is not expressed owing to epigenetic regulation.

control of translation

block initiation of translation stage, regulator proteins attach to 5' end, prevent attachment of ribosomal subunit and initiator tRNA, block translation

protein processing

folding, cleaving, adding sugar groups, targeting for transport

protein degradation

ubiquitin tagging, proteasome degradation

proteasome

organelle that degrades proteins

ubiquitin tagging

mark unwanted proteins with a label "death tag"

emerging virus

viruses that "jump" host, switch species, ebola, sars, bird flu

cells

viruses are not ___

virus

DNA or RNA enclosed in a protein coat

chaperonin

A protein molecule that assists in the proper folding of other proteins.

parasites

lack enzymes for metabolism, lack ribosomes for protein synthesis, need host "machinery

Viral genomes

may be composed of DNA or RNA and may be single- or double-stranded

capsid

Outer protein coat of a virus

capsid

crystal like protein shell, 1-2 types of proteins, many copies of same protein

viral envelope

a lipid bilayer that envelops some viruses, can be derived from host cell membrane

host

virus DNA/RNA enters ____ cell

assimilation

viral DNA/RNA takes over host, reprograms host cell to copy viral nucleic acid and build viral proteins

self assembly

nucleic acid molecules and capsomeres then self-assemble into viral particles and then exit cell

capsomeres

protein subunits that make up capsids

lysis

destruction

rabiees

can infect all mammals

human cold

only cells lining upper respiratory tract of humans

HIV

binds only to specific white blood cells

bacteriophages

viruses that infect bacteria

lytic lifecycle

reproduce virus in bacteria, release virus by rupturing bacterial host

lysogenic lifecycle

integrate viral DNA into bacterial DNA, reproduce with bacteria

restriction enzymes

recognize and cut up foreign DNA

phages

viruses that infect bacteria

retroviruses

have to copy viral RNA into host DNA, enzyme is reverse transcriptase, RNA---> DNA---> mRNA

reverse transcriptase

a polymerase that catalyzes the formation of DNA using RNA as a template

HIV

envelope with glycoproteins for binding to specific WBC, capsid containing 2 RNA strands and 2 copies of reverse transcriptase

budding

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism

protease

enzyme that digests protein

chemokines

A chemical secreted by blood vessel endothelium and monocytes during an immune response to attract phagocytes to an area

cancer viruses

Viruses disrupt the normal growth and division of cells in a host, cause abnormal growth and create tumours

oncogenes

cancer causing genes

prions

infectious proteins

DNA unpacking

1

transcription

2

RNA processing

3

transport to cytoplasm

4

mRNA degradation

5

translation

6

cleavage, transport to destination

7

protein degradation

8